Cable grips or pulling tools for drawing, holding and supporting electrical cables are well known in the art. Many of these prior pulling devices include a braided open wire mesh sleeve formed from interwoven metallic wire strands which may be expanded radially by longitudinal compression to enable them to readily receive the cable and radially contracted by longitudinal stretching to frictionally engage the periphery of the cable. Subsequently applied forces tending to separate the grip from the cable or to move the grip along the cable cause a firmer grip on the cable.
Examples of these prior art pull devices are disclosed in the following U.S. patents: U.S. Pat. No. 832,343 to Scott; U.S. Pat. No. 832,401 to Martin; U.S. Pat. No. 1,114,637 to Nolan; U.S. Pat. No. 1,521,789 to Oswald; U.S. Pat. No. 1,686,250 to Page; U.S. Pat. No. 1,732,410 to Martin; U.S. Pat. No. 1,802,657 to Kellems; U.S. Pat. No. 1,760,074 to Martin; U.S. Pat. No. 1,807,993 to Martin; U.S. Pat. No. 1,994,674 to Inwagen, Jr.; U.S. Pat. No. 2,602,207 to Kellems; U.S. Pat. No. 2,698,150 to Di Palma; U.S. Pat. No. 2,740,178 to Kellems; U.S. Pat. No. 2,766,501 to Kellems; U.S. Pat. No. 3,133,725 to Lanum; U.S. Pat. No. 3,136,844 to Petersen; U.S. Pat. No. 3,137,765 to Lanum; U.S. Pat. No. 3,192,617 to Meyer; U.S. Pat. No. 3,291,507 to Clay; U.S. Pat. No. 3,431,947 to Hines; U.S. Pat. No. 3,551,959 to Mastalski; U.S. Pat. No. 3,599,913 to Di Palma; U.S. Pat. No. 4,055,875 to Strickland; and U.S. Pat. No. 4,368,910 to Fidrych.
Such pulling devices are suitable for the fairly rugged electrical cables, but significant problems arise when the cable to be pulled is small and/or fragile. An example is fiber optic cable which comprises a flexible jacket encasing a single optical fiber or a bundle of optical fibers therein. Such fragile cables can be easily crushed or its optical characteristics can be distorted if the radial compressive forces on the cables are localized and become too great. Also, the optical fiber can be easily broken when subjected to excessive bending forces. In addition, it is typical to have pre-assembled on the end of the fiber optic cable a fragile optical connector receiving one or a bundle of optical fibers therein and secured thereto by epoxy and a crimp or some other suitable fastener. Again, this fragile connector is highly susceptible to crushing radial compressive forces as well as longitudinal tension forces which could easily snap the connector from the cable.
Moreover, fiber optic cable is much smaller in diameter than the typical electrical cable. These small diameters in most cases are much less than the conventional wire mesh grips can adequately hold. Also, the fiber optic connector at the end of the fiber optic cable has a much larger outside diameter than the cable so that a conventional grip selected to fit and adequately grip the cable cannot expand enough to accept the larger connector diameter. Conversely, a grip designed to receive the large diameter connector cannot compress enough to grip the smaller cable diameter. A typical example is a connector with a 0.5 inch outer diameter and a cable with a 0.073 inch outer diameter.
A method presently used to protect a fiber optic cable connector during pulling comprises wrapping the connector in a layer of foam rubber and then inserting this into a plastic sleeve which in turn is inserted into an oversized wire mesh grip. This method, however, is expensive and time consuming since conventional wire mesh grips are relative stiff, thereby creating extreme difficulty in inserting the small and flexible cable with a connector attached. In addition, after assembly of this combination, the holding capability of the oversized wire mesh is marginal and may allow slippage of the cable and pull out of the pre-assembled connector.
In view of the above, it is apparent that there exists a need to provide a pulling device which can be utilized with fragile cable with a connector pre-assembled thereto, and which is inexpensive to manufacture. This invention addresses these needs in the art along with other needs which will become apparent to those skilled in the art once given this disclosure.